Commit 256900b1 authored by Kevin Wolf's avatar Kevin Wolf
Browse files

qcow2: Add qcow2_alloc_clusters_at() 



This function allows to allocate clusters at a given offset in the image
file. This is useful if you want to allocate the second part of an area
that must be contiguous.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
parent bf319ece

block/qcow2-refcount.c

+28 −0
Original line number Diff line number Diff line
@@ -582,6 +582,34 @@ int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size) 
    return offset;

}



int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,

    int nb_clusters)

{

    BDRVQcowState *s = bs->opaque;

    uint64_t cluster_index;

    int i, refcount, ret;



    /* Check how many clusters there are free */

    cluster_index = offset >> s->cluster_bits;

    for(i = 0; i < nb_clusters; i++) {

        refcount = get_refcount(bs, cluster_index++);



        if (refcount < 0) {

            return refcount;

        } else if (refcount != 0) {

            break;

        }

    }



    /* And then allocate them */

    ret = update_refcount(bs, offset, i << s->cluster_bits, 1);

    if (ret < 0) {

        return ret;

    }



    return i;

}



/* only used to allocate compressed sectors. We try to allocate

   contiguous sectors. size must be <= cluster_size */

int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)

block/qcow2.h

+2 −0
Original line number Diff line number Diff line
@@ -193,6 +193,8 @@ int qcow2_refcount_init(BlockDriverState *bs); 
void qcow2_refcount_close(BlockDriverState *bs);



int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size);

int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,

    int nb_clusters);

int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size);

void qcow2_free_clusters(BlockDriverState *bs,

    int64_t offset, int64_t size);